Eco-fertiliser sewage plan a first

Nov 6, 2013

Chichester Observer

A new £2 million sewage treatment facility is being unveiled in Berkshire which provides a sustainable source of environmentally-friendly fertiliser that experts claim could help secure future global food supplies.

Thames Water has created the nutrient-recovery reactor, the first of its kind in Europe, to produce the sanitised phosphorous-based fertiliser from the “unique” waste water coming out of Slough.

A spokesman for the company explained that the price of phosphorous, the key ingredient in fertiliser, had increased by 500% since 2007 as the availability of mined phosphate rock dwindles from non-renewable reserves.

He said the UK uses 138,000 tonnes a year of phosphate fertiliser, all of which is imported from abroad. The reactor will produce 150 tonnes a year.

The spokesman said: “Mineable reserves of phosphorous, in countries like Morocco, the US and China, are set to be completely depleted in 100 years, according to some experts, while others say ‘peak phosphorous’ will occur as early as the mid‐2030s, after which it is expected to become increasingly scarce and expensive.

“This adds to the costs, not to mention the reliance on external sources for such a vital resource, which is used to produce all food consumed by human beings.”

Peter Melchett, policy director at the Soil Association, said: ” With the world’s affordable mineable reserves of phosphorous set to start running out in the next 20 to 30 years, this new technology could offer a solution to securing global food supplies over the coming decades.

“Without fertilisation from phosphorous, wheat crop yields will fall by more than half. Meanwhile, as the planet’s population is predicted to hit nine billion by 2050, demand for food will increase. Sustainable alternative sources of phosphorous, like this reactor at Slough sewage works, are vital if we are to keep pace with this demand.”

The water company spokesman said nutrient-recovery facilities are ideally suited to industrialised areas such as Slough. He said the high-strength organic waste coming from the Slough Trading Estate, immortalised in the BBC television series The Office, was rich in the nutrients ammonia and phosphorous.

He said this causes struvite, which is a rock-like scale on pipes at the sewage works costing Thames Water £200,000 a year to clean.

The facility, built by Vancouver-based Ostara Nutrient Recovery, makes the phosphorous form into struvite in a controlled setting, before turning it into crystalline fertiliser pellets. The company markets this under the brand name Crystal Green, which it says is cleaner than any similar product on the market with lower heavy metal content.